10 Disadvantages of Biofuels

Farmers of corn, soybeans and cotton -- all potential biofuel sources -- are increasingly planting genetically modified versions of those plants [source: United States Department of Agriculture]. This isn't the selective breeding that farmers have practiced for years; genetically modified crops are altered in the lab to tolerate herbicides better, fight off pests or produce higher yields.

In theory, this sounds like a terrific way to keep up with biofuel crop demand. After all, a better harvest would reduce prices and ensure there's enough corn or soybeans on hand to feed and fuel the world, right? But in cases that seem as much science fiction as they are scientific fact, genetically modified crops have accidentally developed unintended -- and sometimes dangerous -- traits.

A prime example of this occurred in the early 2000s. During initial tests of a modified strain of corn, researchers discovered that the crop, which had been engineered to fight off a moth known to prey on corn, produced pollen that could possibly kill larvae of the monarch butterfly. Scientists sounded the alarm, and further tests by academic and industry researchers confirmed that the corn's pollen posed a threat to monarchs. By that time, the corn had been on the market for a season. Thankfully, it didn't sell well, so few fields were planted with it. Had it been the season's popular strain of corn, there could have been an ecological disaster as monarchs migrated through the corn-heavy American Midwest [source: Mellon and Rissler].